Aeronautical Radio, Incorporated (ARINC) standards define parameters for communications between aeronautical devices and systems. The standards support the physical and communication interfaces for transfer of digital information. Radio detection and ranging (RADAR, or commonly referred to as “radar”) systems typically output information that conforms to the ARINC 453 standard, which is a high-speed data protocol for weather radar. The ARINC 453 standard communicates radar information using a 1600 bit word communicated at 1000 kHz.
A radar system emits a directional radio signal along a relatively narrow beam. The radar system then detects returning radio signals reflected by weather phenomena and/or other physical objects. Analysis of the returning radar signals along the particular direction (radial) of the returning radio signal (corresponding to the direction of the emitted radio signal) allows determination of characteristics of the reflecting weather phenomena (and/or other physical objects). For example, the distance range of weather phenomena and/or other physical objects from the radar system may be determined. For certain types of weather phenomena, the intensity of the weather phenomena at various ranges is determinable. For example, the radar system is capable of discerning between light cloud cover versus a heavy thunderstorm having lightning and hail.
As the radar system rotates (sweeps) the position of the radio signal emitter back and forth (or in a circle), the returning radar signals may be analyzed to construct an image of the weather in front of (or around) the aircraft. That is, image data for a plurality of adjacent radials is assembled to form information corresponding to the weather phenomena in front of (or around) the aircraft. The information is presented on a radar display.
The radar information for a radial is presented in a single ARINC 453 word. The 1600 bit ARINC 453 word begins with a 64 bit header followed by a series of 512 sub-words (3 bits each). The header specifies orientation of the radial. The relative location of each sub-word in the word corresponds to a range of a radial. The sub-words contain color information, which is indicative of the nature (e.g., severity) of the detected weather phenomena and/or other physical objects. For example, the color black indicates an absence of weather phenomena (no returning reflected radar signal at that range).
Aircraft personnel may use various types of portable auxiliary equipment. Such equipment may be commonly referred to as an “electronic flight bag” (EFB) or an “electronic travel bag” (ETB), generally referred to as EFBs herein. EFBs are connectable to aviation electronics of the airplane via ports, busses, or other suitable connectors. EFBs conform their connections to communicate under the ARINC 429 standard, which is a relatively low speed data protocol (particularly with respect to the ARINC 453 standard used by radars). ARINC 429 supports a low speed data transfer mode (12.5 to 14.5 kHz) or a high speed data transfer mode (100 kHz) based upon a 32 bit word structure.
EFBs may include a display. At times, it may be desirable to have the EFB display present radar information. However, weather radar information available under the ARINC 453 standard (1600 bit words communicated at 1000 kHz) cannot be communicated over a connector operating under the ARINC 429 standard with sufficient speed to present radar information on a real time basis. That is, the inherent delay in communicating the weather radar information (generated in 1600 bit words at a 1000 kHz rate) over the ARINC 429 connector (32 bit words communicated at the low speed or the high speed ARINC 429 rates) would be so great that the presented radar weather image on the EFB display would not be of any useful value to aircraft personnel.